: The proposed research will assess and follow preschool children identified as having clinically significant disruptive behavior problems. What is unique about this study is the selection of major variables based on current developmental theories of cognitive, communicative, and affective growth, including the constructs of attachment and emotion regulation which have not previously been applied to the conceptualization of clinic-referred children with behavior disorders. These variables, in addition to microanalytic measures of mother-child interaction, family environment, and other ecological factors, will be assessed to determine: 1) which variables discriminate problem from nonproblem children at initial assessment, and 2) which variables predict psychiatric dysfunction one and two years later. A clinic-referred sample of 90 oppositional children (3.5 to 5.5 years of age) and a matched nonproblem group of 85 preschoolers will be followed over a two year period. At initial assessment and again one and two years later, a structured interview (Diagnostic Interview for Children and Adolescents) will be used to determine diagnostic status. Observed mother-child interaction will be scored for verbal and nonverbal interaction, affective expression, nature of joint planning and security of mother-child attachment. Mothers' internal representations of attachment will be assessed using the Adult Attachment Interview. Children will be individually tested for cognitive, visual-motor and affective development, and parents will provide information about personal, family and ecological factors. Hypotheses to be tested are related to: a) the predictive value of theoretically-based, developmentally-sensitive measures versus variables based on operant or social learning theory formulations; b) clinic-comparison group differences on measures of parent-child interaction and attachment; and c) the interaction of clinic status and family structure over time.